I went out to use the hot tub the other day and the heater was not working. The internal breaker on the tub itself was tripped, so I reset it. The tub runs fine and heats the water as long as the jets are running. Within minutes of turning the jets off, the breaker will trip again. I had the jets running for almost 8 hours the other day trying to reheat the water after the initial trip, and it ran fine the whole time. Within 5 minutes of turning off the jets (the heater should have still been running) the breaker tripped. Turning the jets off in and of itself is not tripping the breaker, because I can immediately turn them back on once I turn them off. It has to sit a few minutes before the breaker will trip. And once it trips, it takes a few more minutes before it will let me reset it and the jets/heater will function again (before this time, resetting the breaker does nothing). I can't see any obvious reason for this to be happening, and nothing has changed with the tub. It's kept outdoors, we've lived in the house 4 years and the tub is even older. I need to keep it heating reliably so the pipes won't freeze in the winter, or I'll have to drain it for the season.

This is just a guess but I would say the running water of the jets is keeping the heater from over heating maybe. When the jets are shut off it takes a few minutes for it to heat up to a point where it trips. Then it takes a while before it cools down enough for the breaker to be reset. This is just a guess as I don't know how a hot tubs plumbing is run. Hope it helps you out.